package im.actor.keygen.curve25519;

// Disabling Bounds checks for speeding up calculations

/*-[
#define J2OBJC_DISABLE_ARRAY_BOUND_CHECKS 1
]-*/

public class sc_reduce {

//CONVERT #include "sc.h"
//CONVERT #include "long.h"
//CONVERT #include "crypto_uint32.h"
//CONVERT #include "long.h"

    public static long load_3(byte[] in, int index) {
        long result;
        result = ((long) in[index + 0]) & 0xFF;
        result |= (((long) in[index + 1]) << 8) & 0xFF00;
        result |= (((long) in[index + 2]) << 16) & 0xFF0000;
        return result;
    }

    public static long load_4(byte[] in, int index) {
        long result;
        result = (((long) in[index + 0]) & 0xFF);
        result |= ((((long) in[index + 1]) << 8) & 0xFF00);
        result |= ((((long) in[index + 2]) << 16) & 0xFF0000);
        result |= ((((long) in[index + 3]) << 24) & 0xFF000000L);
        return result;
    }

/*
Input:
  s[0]+256*s[1]+...+256^63*s[63] = s

Output:
  s[0]+256*s[1]+...+256^31*s[31] = s mod l
  where l = 2^252 + 27742317777372353535851937790883648493.
  Overwrites s in place.
*/

    public static void sc_reduce(byte[] s) {
        long s0 = 2097151 & load_3(s, 0);
        long s1 = 2097151 & (load_4(s, 2) >>> 5);
        long s2 = 2097151 & (load_3(s, 5) >>> 2);
        long s3 = 2097151 & (load_4(s, 7) >>> 7);
        long s4 = 2097151 & (load_4(s, 10) >>> 4);
        long s5 = 2097151 & (load_3(s, 13) >>> 1);
        long s6 = 2097151 & (load_4(s, 15) >>> 6);
        long s7 = 2097151 & (load_3(s, 18) >>> 3);
        long s8 = 2097151 & load_3(s, 21);
        long s9 = 2097151 & (load_4(s, 23) >>> 5);
        long s10 = 2097151 & (load_3(s, 26) >>> 2);
        long s11 = 2097151 & (load_4(s, 28) >>> 7);
        long s12 = 2097151 & (load_4(s, 31) >>> 4);
        long s13 = 2097151 & (load_3(s, 34) >>> 1);
        long s14 = 2097151 & (load_4(s, 36) >>> 6);
        long s15 = 2097151 & (load_3(s, 39) >>> 3);
        long s16 = 2097151 & load_3(s, 42);
        long s17 = 2097151 & (load_4(s, 44) >>> 5);
        long s18 = 2097151 & (load_3(s, 47) >>> 2);
        long s19 = 2097151 & (load_4(s, 49) >>> 7);
        long s20 = 2097151 & (load_4(s, 52) >>> 4);
        long s21 = 2097151 & (load_3(s, 55) >>> 1);
        long s22 = 2097151 & (load_4(s, 57) >>> 6);
        long s23 = (load_4(s, 60) >>> 3);
        long carry0;
        long carry1;
        long carry2;
        long carry3;
        long carry4;
        long carry5;
        long carry6;
        long carry7;
        long carry8;
        long carry9;
        long carry10;
        long carry11;
        long carry12;
        long carry13;
        long carry14;
        long carry15;
        long carry16;

        s11 += s23 * 666643;
        s12 += s23 * 470296;
        s13 += s23 * 654183;
        s14 -= s23 * 997805;
        s15 += s23 * 136657;
        s16 -= s23 * 683901;
        s23 = 0;

        s10 += s22 * 666643;
        s11 += s22 * 470296;
        s12 += s22 * 654183;
        s13 -= s22 * 997805;
        s14 += s22 * 136657;
        s15 -= s22 * 683901;
        s22 = 0;

        s9 += s21 * 666643;
        s10 += s21 * 470296;
        s11 += s21 * 654183;
        s12 -= s21 * 997805;
        s13 += s21 * 136657;
        s14 -= s21 * 683901;
        s21 = 0;

        s8 += s20 * 666643;
        s9 += s20 * 470296;
        s10 += s20 * 654183;
        s11 -= s20 * 997805;
        s12 += s20 * 136657;
        s13 -= s20 * 683901;
        s20 = 0;

        s7 += s19 * 666643;
        s8 += s19 * 470296;
        s9 += s19 * 654183;
        s10 -= s19 * 997805;
        s11 += s19 * 136657;
        s12 -= s19 * 683901;
        s19 = 0;

        s6 += s18 * 666643;
        s7 += s18 * 470296;
        s8 += s18 * 654183;
        s9 -= s18 * 997805;
        s10 += s18 * 136657;
        s11 -= s18 * 683901;
        s18 = 0;

        carry6 = (s6 + (1 << 20)) >> 21;
        s7 += carry6;
        s6 -= carry6 << 21;
        carry8 = (s8 + (1 << 20)) >> 21;
        s9 += carry8;
        s8 -= carry8 << 21;
        carry10 = (s10 + (1 << 20)) >> 21;
        s11 += carry10;
        s10 -= carry10 << 21;
        carry12 = (s12 + (1 << 20)) >> 21;
        s13 += carry12;
        s12 -= carry12 << 21;
        carry14 = (s14 + (1 << 20)) >> 21;
        s15 += carry14;
        s14 -= carry14 << 21;
        carry16 = (s16 + (1 << 20)) >> 21;
        s17 += carry16;
        s16 -= carry16 << 21;

        carry7 = (s7 + (1 << 20)) >> 21;
        s8 += carry7;
        s7 -= carry7 << 21;
        carry9 = (s9 + (1 << 20)) >> 21;
        s10 += carry9;
        s9 -= carry9 << 21;
        carry11 = (s11 + (1 << 20)) >> 21;
        s12 += carry11;
        s11 -= carry11 << 21;
        carry13 = (s13 + (1 << 20)) >> 21;
        s14 += carry13;
        s13 -= carry13 << 21;
        carry15 = (s15 + (1 << 20)) >> 21;
        s16 += carry15;
        s15 -= carry15 << 21;

        s5 += s17 * 666643;
        s6 += s17 * 470296;
        s7 += s17 * 654183;
        s8 -= s17 * 997805;
        s9 += s17 * 136657;
        s10 -= s17 * 683901;
        s17 = 0;

        s4 += s16 * 666643;
        s5 += s16 * 470296;
        s6 += s16 * 654183;
        s7 -= s16 * 997805;
        s8 += s16 * 136657;
        s9 -= s16 * 683901;
        s16 = 0;

        s3 += s15 * 666643;
        s4 += s15 * 470296;
        s5 += s15 * 654183;
        s6 -= s15 * 997805;
        s7 += s15 * 136657;
        s8 -= s15 * 683901;
        s15 = 0;

        s2 += s14 * 666643;
        s3 += s14 * 470296;
        s4 += s14 * 654183;
        s5 -= s14 * 997805;
        s6 += s14 * 136657;
        s7 -= s14 * 683901;
        s14 = 0;

        s1 += s13 * 666643;
        s2 += s13 * 470296;
        s3 += s13 * 654183;
        s4 -= s13 * 997805;
        s5 += s13 * 136657;
        s6 -= s13 * 683901;
        s13 = 0;

        s0 += s12 * 666643;
        s1 += s12 * 470296;
        s2 += s12 * 654183;
        s3 -= s12 * 997805;
        s4 += s12 * 136657;
        s5 -= s12 * 683901;
        s12 = 0;

        carry0 = (s0 + (1 << 20)) >> 21;
        s1 += carry0;
        s0 -= carry0 << 21;
        carry2 = (s2 + (1 << 20)) >> 21;
        s3 += carry2;
        s2 -= carry2 << 21;
        carry4 = (s4 + (1 << 20)) >> 21;
        s5 += carry4;
        s4 -= carry4 << 21;
        carry6 = (s6 + (1 << 20)) >> 21;
        s7 += carry6;
        s6 -= carry6 << 21;
        carry8 = (s8 + (1 << 20)) >> 21;
        s9 += carry8;
        s8 -= carry8 << 21;
        carry10 = (s10 + (1 << 20)) >> 21;
        s11 += carry10;
        s10 -= carry10 << 21;

        carry1 = (s1 + (1 << 20)) >> 21;
        s2 += carry1;
        s1 -= carry1 << 21;
        carry3 = (s3 + (1 << 20)) >> 21;
        s4 += carry3;
        s3 -= carry3 << 21;
        carry5 = (s5 + (1 << 20)) >> 21;
        s6 += carry5;
        s5 -= carry5 << 21;
        carry7 = (s7 + (1 << 20)) >> 21;
        s8 += carry7;
        s7 -= carry7 << 21;
        carry9 = (s9 + (1 << 20)) >> 21;
        s10 += carry9;
        s9 -= carry9 << 21;
        carry11 = (s11 + (1 << 20)) >> 21;
        s12 += carry11;
        s11 -= carry11 << 21;

        s0 += s12 * 666643;
        s1 += s12 * 470296;
        s2 += s12 * 654183;
        s3 -= s12 * 997805;
        s4 += s12 * 136657;
        s5 -= s12 * 683901;
        s12 = 0;

        carry0 = s0 >> 21;
        s1 += carry0;
        s0 -= carry0 << 21;
        carry1 = s1 >> 21;
        s2 += carry1;
        s1 -= carry1 << 21;
        carry2 = s2 >> 21;
        s3 += carry2;
        s2 -= carry2 << 21;
        carry3 = s3 >> 21;
        s4 += carry3;
        s3 -= carry3 << 21;
        carry4 = s4 >> 21;
        s5 += carry4;
        s4 -= carry4 << 21;
        carry5 = s5 >> 21;
        s6 += carry5;
        s5 -= carry5 << 21;
        carry6 = s6 >> 21;
        s7 += carry6;
        s6 -= carry6 << 21;
        carry7 = s7 >> 21;
        s8 += carry7;
        s7 -= carry7 << 21;
        carry8 = s8 >> 21;
        s9 += carry8;
        s8 -= carry8 << 21;
        carry9 = s9 >> 21;
        s10 += carry9;
        s9 -= carry9 << 21;
        carry10 = s10 >> 21;
        s11 += carry10;
        s10 -= carry10 << 21;
        carry11 = s11 >> 21;
        s12 += carry11;
        s11 -= carry11 << 21;

        s0 += s12 * 666643;
        s1 += s12 * 470296;
        s2 += s12 * 654183;
        s3 -= s12 * 997805;
        s4 += s12 * 136657;
        s5 -= s12 * 683901;
        s12 = 0;

        carry0 = s0 >> 21;
        s1 += carry0;
        s0 -= carry0 << 21;
        carry1 = s1 >> 21;
        s2 += carry1;
        s1 -= carry1 << 21;
        carry2 = s2 >> 21;
        s3 += carry2;
        s2 -= carry2 << 21;
        carry3 = s3 >> 21;
        s4 += carry3;
        s3 -= carry3 << 21;
        carry4 = s4 >> 21;
        s5 += carry4;
        s4 -= carry4 << 21;
        carry5 = s5 >> 21;
        s6 += carry5;
        s5 -= carry5 << 21;
        carry6 = s6 >> 21;
        s7 += carry6;
        s6 -= carry6 << 21;
        carry7 = s7 >> 21;
        s8 += carry7;
        s7 -= carry7 << 21;
        carry8 = s8 >> 21;
        s9 += carry8;
        s8 -= carry8 << 21;
        carry9 = s9 >> 21;
        s10 += carry9;
        s9 -= carry9 << 21;
        carry10 = s10 >> 21;
        s11 += carry10;
        s10 -= carry10 << 21;

        s[0] = (byte) (s0 >> 0);
        s[1] = (byte) (s0 >> 8);
        s[2] = (byte) ((s0 >> 16) | (s1 << 5));
        s[3] = (byte) (s1 >> 3);
        s[4] = (byte) (s1 >> 11);
        s[5] = (byte) ((s1 >> 19) | (s2 << 2));
        s[6] = (byte) (s2 >> 6);
        s[7] = (byte) ((s2 >> 14) | (s3 << 7));
        s[8] = (byte) (s3 >> 1);
        s[9] = (byte) (s3 >> 9);
        s[10] = (byte) ((s3 >> 17) | (s4 << 4));
        s[11] = (byte) (s4 >> 4);
        s[12] = (byte) (s4 >> 12);
        s[13] = (byte) ((s4 >> 20) | (s5 << 1));
        s[14] = (byte) (s5 >> 7);
        s[15] = (byte) ((s5 >> 15) | (s6 << 6));
        s[16] = (byte) (s6 >> 2);
        s[17] = (byte) (s6 >> 10);
        s[18] = (byte) ((s6 >> 18) | (s7 << 3));
        s[19] = (byte) (s7 >> 5);
        s[20] = (byte) (s7 >> 13);
        s[21] = (byte) (s8 >> 0);
        s[22] = (byte) (s8 >> 8);
        s[23] = (byte) ((s8 >> 16) | (s9 << 5));
        s[24] = (byte) (s9 >> 3);
        s[25] = (byte) (s9 >> 11);
        s[26] = (byte) ((s9 >> 19) | (s10 << 2));
        s[27] = (byte) (s10 >> 6);
        s[28] = (byte) ((s10 >> 14) | (s11 << 7));
        s[29] = (byte) (s11 >> 1);
        s[30] = (byte) (s11 >> 9);
        s[31] = (byte) (s11 >> 17);
    }


}
